1. Field of the Invention
The present invention relates to a gas charging device which reversely supplies fresh gas such as liquefied gas and compressed gas from a gas outlet of a pressure reducing valve to a gas inlet thereof.
2. Explanation of Related Art
The pressure reducing valve has its gas outlet communicated with an actuation chamber. When the gas outlet has its pressure increased, a pressure reducing member is moved in a closing direction by a closing force resulting from a pressure of the actuation chamber. This reduces gas to be taken out of the gas outlet of the pressure reducing valve. Therefore, in the event high pressure gas tries to reversely flow from the gas outlet of the pressure reducing valve into the gas inlet thereof, the high pressure gas within the gas outlet flows into the actuation chamber to move the pressure reducing member in the closing direction and then the pressure reducing valve closes. Thus in the case where high pressure fresh gas is supplied to a gas cylinder with the pressure reducing valve of this type, it was required, for example, to form a gas charging passage which bypasses the pressure reducing valve or to provide a gas charging port separate from a gas take-out port which communicates with the pressure reducing valve so that the fresh gas might not pass through the pressure reducing valve.
Japanese Patent Public Disclosure No. 9-170672 disclosed a conventional example of the pressure reducing valve through which fresh gas can be charged from a gas outlet into a gas cylinder, so as to solve the foregoing problem.
This pressure reducing valve comprises a housing including a pressure reducing valve chamber, an inlet passage which flows taken-out gas into the pressure reducing valve chamber, an outlet passage which discharges the taken-out gas from the pressure reducing valve chamber, and a pressure reducing member inserted into the pressure reducing valve chamber so as to control flow-out of the gas from the outlet passage. The pressure reducing member has a piston member which comprises a first piston near the pressure reducing member and a second piston radially larger and positioned further than the first piston. It also includes an urging means which urges the piston member in a valve-opening direction. Besides, an actuation chamber is formed on the further side of the second piston. The actuation chamber communicates with the outlet passage through a communication passage.
And the taken-out gas which flows in from the inlet passage moves the piston member in the valve-opening direction together with the urging means and flows from a gap between the pressure reducing member and an opposite pressure reducing valve seat out to the outlet passage to be reduced. A pressure of the taken-out gas at the outlet passage is transmitted to the actuation chamber through the communication passage. The pressure within the actuation chamber pushes the second piston to return the piston member in a valve-closing direction.
A movable means is arranged within the communication passage hermetically and slidably and is urged toward the outlet passage by a spring.
When charging high pressure fresh gas into a gas cylinder with this pressure reducing valve, a charging mouthpiece provided with a pushing portion at its leading end is attached to the outlet passage. The pushing portion inserted into the outlet passage pushes the movable means to move it toward the actuation chamber against the urging force of the spring. The movable means has an end which inhibits the fresh gas from flowing into the actuation chamber when brought into contact with a housing by the above movement. This prevents addition of a force onto the second piston in the valve-closing direction and thereby keeps the pressure reducing valve open. Then the high pressure fresh gas flows into the gas cylinder through the pressure reducing valve.
The conventional technique is excellent in that it can effect the fresh gas charging through the pressure reducing valve and need not provide a charging passage or the like which bypasses the pressure reducing valve, but it has the following problems:
(1) In order to inhibit the flow-in of the fresh gas from the gas outlet to the actuation chamber when charging, a movable means has to be provided hermetically and slidably within the communication passage. This complicates the structure of the pressure reducing valve.
It is considered to construct the movable means by part of the piston member in order to solve that problem. However, the movable means moves in the valve-opening direction so as to prevent the gas from flowing into the actuation chamber. On the other hand, the piston member is urged in the valve-opening direction through the urging means. Consequently, in the event the movable means is constructed by the part of the piston member, when taking the gas out of the gas cylinder, the piston member has already moved toward the valve opening side and therefore the taken-out gas does not flow into the actuation chamber, which entails a problem of being unable to reduce its pressure.
(2) The pushing portion provided at the leading end of the charging mouthpiece is inserted into the outlet passage so as to push the movable means within the communication passage when charging the fresh gas. The movable means must be firmly pushed for inhibiting the flow of the fresh gas from the outlet passage into the actuation chamber and therefore the pushing portion needs a predetermined size. Further, the outlet passage into which the pushing portion is inserted must have its sectional area increased more than that of the pushing portion so as to be able to secure a gas charging passage between the inserted pushing portion and itself. This results in increasing a sealing area of the pressure reducing member which seals this outlet passage. And the first piston has its sectional area increased more than the sealing area of the pressure reducing member so that it can move in the valve-opening direction with the pressure of the gas which flows into the pressure reducing valve chamber when taking out the gas. In addition, the second piston is radially larger than the first piston. As a result, there is caused a problem that the pressure reducing valve become quite large in correspondence with the size of the pushing portion.
The present invention has an object to seal the flow-in of fresh gas from the gas outlet to the actuation chamber by a sealing means which is small and has a simple structure and to make compact a pressure reducing valve to which the present gas charging device is applied.
In order to accomplish the above-mentioned object, the present invention has constructed a gas charging device in the following manner, for example, as shown in FIGS. 1 to 3.
The gas charging device is provided with a charging nozzle 34 which has a nozzle leading end portion 45. There is provided within the charging nozzle 34 a charging passage in communication with the gas outlet 7b. Attached to the charging nozzle 34 is a push member 37. The push member 37 is provided with a projection 40, which sticks out toward the pressure reducing member 17 ahead of the nozzle leading end portion 45. The projection 40 is provided with a sealing means 41, which is directed from the gas outlet 7b to the actuation chamber 29 so that it comes into sealing contact with the portion 43 to be sealed. This contact inhibits the fresh gas supplied to the gas outlet 7b from flowing to the actuation chamber 29.
The gas charging device is provided with a charging nozzle 34 which has a nozzle leading end portion 45. There is provided within the charging nozzle 34 a charging passage 35 which communicates with the gas outlet 7b. Attached to the charging nozzle 34 is a push member 37. The push member 37 is provided with a projection 40, which sticks out toward the pressure reducing member 17 ahead of the nozzle leading end portion 45. The projection 40 is provided with a sealing means 41, which is directed from the gas outlet 7b to the actuation chamber 29 so that it comes into sealing contact with the portion 43 to be sealed. This contact inhibits the fresh gas supplied to the gas outlet 7b from flowing to the actuation chamber 29.
The present invention functions as follows.
When taking out gas, if the taken-out gas flows from the gas inlet into the pressure reducing valve chamber, a pressure of the gas separates the pressure reducing member from the pressure reducing valve seat. This allows the taken-out gas to flow from a gap between the pressure reducing member and the pressure reducing valve seat out to the outlet passage while it is being reduced. The pressure of the taken-out gas which has flowed out to the outlet passage is transmitted to the actuation chamber through the communication passage. The pressure within the actuation chamber pushes the pressure reducing member to return it toward the pressure reducing valve seat. The pressure reducing member moves close to and away from the pressure reducing valve seat by a closing force resulting from the gas pressure within the actuation chamber and an opening force attributable to the gas pressure of the gas inlet. This reduces the pressure of the taken-out gas which flows out of the gas outlet.
On the other hand, when supplying fresh gas from the gas outlet of the pressure reducing valve to the gas inlet thereof, a charging mouthpiece is attached to the outlet passage. And the sealing means provided in the projection is directed from the gas outlet to the actuation chamber so that it comes into contact with the portion to be sealed, which is provided in the end surface of the peripheral wall of the communication passage. This seals the communication passage as it is covered with the sealing means and inhibits the flow of the fresh gas from the gas outlet into the actuation chamber. As a result, the pressure reducing member is pushed by the fresh gas pressure within the gas outlet to move toward the valve-opening side and the fresh gas is supplied to the gas inlet of the pressure reducing valve chamber.
The present invention is constructed and functions as mentioned above. Therefore, it has the following advantages.
(1) Being provided in the end surface of its peripheral wall with a portion to be sealed so that the portion to be sealed faces the gas outlet, the communication passage can be sealed only by directing the sealing means of the charging mouthpiece from the gas outlet to the actuation chamber so that it comes into contact with the portion to be sealed. This can supply the fresh gas from the gas outlet of the pressure reducing valve to the gas inlet thereof without closing the pressure reducing member. In consequence, there is no need of providing the movable member required by the conventional technique to result in the possibility of simplifying the structure of the pressure reducing valve and besides removing the space for accommodating the movable member to make the pressure reducing valve compact.
(2) Further, the portion to be sealed, which is provided in the end surface of the peripheral wall of the communication passage, faces the gas outlet. The communication passage can be sealed as it is covered with the sealing means only by directing the sealing means from the gas outlet to the actuation chamber so that it comes into sealing contact with the portion to be sealed. Therefore, the sealing means to be provided in the projection can be readily downsized, which results in the possibility of reducing the diameter of the communication passage to form the pressure reducing member into a small structure. In consequence, the pressure reducing valve can be made compact as a whole.
The push member can be supported by the charging nozzle so as to advance and retreat with respect to the pressure reducing member and be urged toward the pressure reducing member by an urging means. In this case, since the urging means pushes the push member, the sealing means can be firmly pushed to the portion to be sealed, which results in the possibility of assuredly sealing the communication passage. As for the urging means, it is possible to employ a spring or the like resilient member. Alternatively, it is possible to use pressure of gas such as fresh gas or to employ a combination of these ones.
A gas discharge port which communicates the charging passage within the charging nozzle with the gas outlet may be provided in the nozzle leading end portion. In this case, the projection of the push member can be formed in the shape of a rod. In the event the projection is formed cylindrical, the gas discharge port may be provided in the cylindrical wall to communicate the charging passage with the gas outlet through an interior area of the cylindrical projection and the gas discharge port.